Slipping Transmission.

[dougie]

The transmission on my 2003 H2 Hummer has started to slip especially from 1st to 2nd and is slow to change. Has anyone advice as to what is wrong because as a senior citizen repair shops take advantage because of my age and always repair as expensive as possible. When the shifter recently stuck in neutral the shop quoted between $100 and $1,000 to repair the problem. It helps if I appear to know what the problem is when I take the vehicle into the shop. Please help.